1. Field of the Invention
This invention relates to a stimulable phosphor sheet feeding and storing mechanism which takes out a stimulable phosphor sheet which has been stored in a stimulable phosphor sheet cassette from the cassette and feeds it to a radiation image recording and reproducing system or the like, and stores another stimulable phosphor sheet in the cassette. This invention also relates to a stimulable phosphor sheet cassette which is suitable for use in the stimulable phosphor sheet feeding and storing mechanism.
2. Description of the Related Art
When certain kinds of phosphors are exposed to radiation such as X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays or ultraviolet rays, they store part of the energy of the radiation. Then, when the phosphor which has been exposed to the radiation is exposed to stimulating rays such as visible light, light is emitted by the phosphor in proportion to the amount of energy stored during exposure to the radiation. A phosphor exhibiting such properties is referred to as a stimulable phosphor.
As disclosed in U.S. Pat. Nos. 4,258,264, 4,276,473, 4,315,318 and 4,387,428 and Japanese Unexamined Patent Publication No. 56(1981)-11395, it has been proposed to use stimulable phosphors in radiation image recording and reproducing systems. Specifically, a sheet provided with a layer of the stimulable phosphor (hereinafter referred to as a stimulable phosphor sheet) is first exposed to radiation which has passed through an object such as the human body in order to store a radiation image of the object thereon, and is then scanned with stimulating rays, such as a laser beam, which cause it to emit light in proportion to the amount of energy stored during exposure to the radiation. The light emitted by the stimulable phosphor sheet upon stimulation thereof is photoelectrically detected and converted into an electric image signal, which is used when the radiation image of the object is reproduced as a visible image on a recording material such as photographic film, a display device such as a cathode ray tube (CRT), or the like.
Since the stimulable phosphor sheet has generally been stored in a light-tight cassette and is loaded in the radiation image recording system in the state, it will be convenient to arrange a radiation image read-out system so that the stimulable phosphor sheet can be loaded therein as it is in the cassette and a recovered stimulable phosphor sheet can be taken out from the system as it is stored in the cassette.
This applicant has proposed a radiation image read-out system having a stimulable phosphor sheet feeding and storing mechanism which automatically takes out a stimulable phosphor sheet from a cassette and feeds it to the read-out section, and automatically stores in the cassette a stimulable phosphor sheet the radiation image on which has been read out and erased. See U.S. Pat. No. 4,777,365, for example.
Though the stimulable phosphor sheet feeding and storing mechanism is very useful, a long time is required for feeding and storing the stimulable phosphor sheet since the mechanism must open and close the lid of the cassette in order to take out the sheet from the cassette and to store the same in the cassette and feeding the sheet involves lifting of the sheet by suction. Further, the means for applying suction to the sheet such as a suction arm makes the stimulable phosphor sheet feeding and storing mechanism complex in structure and adds to the manufacturing cost of the same.
Further, the openable lid adds to the manufacturing cost of the cassette.